In the past, there have been many different types of backwater valves. For example. U.S. Pat. No. 4,503,881 disclosed an automatic counterbalanced sewer valve with a float closure. Also, U.S. Pat. No. 5,406,972 to Coscarella et al. disclosed a backwater valve with a float mechanism, as did U.S. Pat. No. 2,786,542 to Orfei et al.